This document specifies the ISO 639 language code and establishes the harmonized terminology and general principles of language coding. It provides rules for the selection, formation, presentation and use of language identifiers as well as language reference names. It also gives provisions (i.e. principles, rules and guidelines) for the selection, formation and presentation of language names in English and French. Furthermore, it introduces provisions for the adoption of standardized language code elements using language names other than English or French.

NOTE English, French and Russian are the official ISO languages.

In addition, this document gives guidance on the use of language identifiers and describes their possible combination with identifiers of other codes.

Specifically excluded from the ISO 639 language code are reconstructed languages or formal languages, such as computer programming languages and markup languages.

The ISO 639 language code is maintained by the ISO 639 Maintenance Agency (ISO 639/MA) (see Annex B).